wpiutil: Add C++ libuv wrappers (#1166)

- Provide an EventLoopRunner to run uv::Loop on a separate thread.

- Add raw_ostream wrapper for uv::Buffer.

wpiutil/src/main/native/include/wpi/uv/Tty.h

@@ -0,0 +1,88 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2018 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#ifndef WPIUTIL_WPI_UV_TTY_H_
+#define WPIUTIL_WPI_UV_TTY_H_
+
+#include <uv.h>
+
+#include <memory>
+#include <utility>
+
+#include "wpi/uv/Stream.h"
+
+namespace wpi {
+namespace uv {
+
+class Loop;
+class Tty;
+
+/**
+ * TTY handle.
+ * TTY handles represent a stream for the console.
+ */
+class Tty final : public StreamImpl<Tty, uv_tty_t> {
+  struct private_init {};
+
+ public:
+  explicit Tty(const private_init&) {}
+  ~Tty() noexcept override = default;
+
+  /**
+   * Create a TTY handle.
+   *
+   * @param loop Loop object where this handle runs.
+   * @param fd File descriptor, usually 0=stdin, 1=stdout, 2=stderr
+   * @param readable Specifies if you plan on calling StartRead().  stdin is
+   *                 readable, stdout is not.
+   */
+  static std::shared_ptr<Tty> Create(Loop& loop, uv_file fd, bool readable);
+
+  /**
+   * Create a TTY handle.
+   *
+   * @param loop Loop object where this handle runs.
+   * @param fd File descriptor, usually 0=stdin, 1=stdout, 2=stderr
+   * @param readable Specifies if you plan on calling StartRead().  stdin is
+   *                 readable, stdout is not.
+   */
+  static std::shared_ptr<Tty> Create(const std::shared_ptr<Loop>& loop,
+                                     uv_file fd, bool readable) {
+    return Create(*loop, fd, readable);
+  }
+
+  /**
+   * Set the TTY using the specified terminal mode.
+   *
+   * @param mode terminal mode
+   */
+  void SetMode(uv_tty_mode_t mode) {
+    int err = uv_tty_set_mode(GetRaw(), mode);
+    if (err < 0) ReportError(err);
+  }
+
+  /**
+   * Reset TTY settings to default values for the next process to take over.
+   * Typically called when the program exits.
+   */
+  void ResetMode() { Invoke(&uv_tty_reset_mode); }
+
+  /**
+   * Gets the current window size.
+   * @return Window size (pair of width and height).
+   */
+  std::pair<int, int> GetWindowSize() {
+    int width = 0, height = 0;
+    Invoke(&uv_tty_get_winsize, GetRaw(), &width, &height);
+    return std::make_pair(width, height);
+  }
+};
+
+}  // namespace uv
+}  // namespace wpi
+
+#endif  // WPIUTIL_WPI_UV_TTY_H_